1. Field of the Invention
The present invention relates generally to an electrical connector for use with a circuit board, and more particularly to an improvement in an electrical connector used to be mounted on and connected electrically with a circuit board for coupling with a mate electrical connector mounted on another circuit board to be electrically connected with the same.
2. Description of the Prior Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Various kinds of electric or electronic parts are built even in a relatively small-sized electronic apparatus such as a portable telephone or the like. A major part of those parts are dispersedly mounted on, for example, a couple of separate circuit boards to fulfill their respective functions. In the relatively small-sized electronic apparatus, having an eye to the couple of separate circuit boards on which the electric or electronic parts are mounted, it is likely that one of the separate circuit boards is required to be laid on top of the other of the separate circuit boards for reducing a space occupied thereby when the separate circuit boards are electrically connected with each other. Such an electrical connection between the separate circuit boards wherein one is laid on top of the other is hereinafter referred to as an electrical piling connection.
In general, when a plurality of circuit boards, such as solid circuit boards, are electrically connected with one another, a plurality of electrical connectors are mounted on the circuit boards, respectively, and one of the electrical connectors is coupled with another electrical connector so as to connect one of the circuit boards electrically with another circuit board. In case of the electrical piling connection mentioned above, first and second electrical connectors are mounted respectively on the separate circuit boards to be coupled with each other. The first electrical connector is formed into a plug type connector and the second electrical connector is formed into a receptacle type connector to be a mate electrical connector for the first electrical connector, so that the plug type connector is engaged with the receptacle type connector when the separate circuit boards are put in a condition of the electrical piling connection.
In such a case, the plug type connector has an insulating housing provided to be fixed to one of the separated circuit boards and the receptacle connector has another insulating housing provided to be fixed to the other of the separated circuit boards. The insulating housing of the plug type connector is provided thereon with an engaging projection formed to elongate in a longitudinal direction of the insulating housing of the plug type connector to be inserted into an engaging groove formed on the insulating housing of the receptacle connector to elongate in a longitudinal direction of the insulating housing of the receptacle connector. The engaging projection formed on the insulating housing of the plug type connector and the elongating groove formed on the insulating housing of the receptacle type connector constitute jointly a pair of engaging portions operative to engage with each other.
As to one of the plug type and receptacle type connectors, for example, the plug type connector, the insulating housing of the plug type connector is provided thereon with a plurality of plug side signal contacts arranged along the engaging projection formed on the insulating housing of the plug type connector to be connected respectively with a plurality of signal terminals provided on the separate circuit board to which the insulating housing of the plug type connector is fixed (hereinafter, referred to as a plug side circuit board) and provided thereon also with a plug side ground contact to be connected with a ground terminal provided on the plug side circuit board. Such a plug type connector having the insulating housing on which the plug side signal contacts and the plug side ground contact are provided is usually provided further with a conductive shell member which covers partially the outside of the engaging projection formed on the insulating housing of the plug type connector and is connected with a grounding portion of the plug side circuit board including the ground terminal provided on the plug side circuit board so as to be supplied with a ground potential.
When the engaging projection formed on the insulating housing of the plug type connector is inserted into the engaging groove formed on the insulating housing of the receptacle type connector and thereby the plug type connector is coupled with the receptacle type connector, so that the plug side circuit board and the separate circuit board to which the insulating housing of the receptacle type connector is fixed (hereinafter, referred to as a receptacle side circuit board) are put in the condition of the electrical piling connection, the plug side signal contacts come into contact respectively with a plurality of receptacle side signal contacts, which are arranged along the engaging groove on the insulating housing of the receptacle type connector and connected respectively with a plurality of signal terminals provided on the receptacle side circuit board, to be electrically connected with the same, and the plug side ground contact comes into contact with a receptacle side ground contact, which is provided on the insulating housing of the receptacle type connector and connected with a ground terminal provided on the receptacle side circuit board, to be electrically connected with the same. As a result, the signal terminals provided on the plug side circuit board are electrically connected through the plug type and receptacle type connectors with the signal terminals provided on the receptacle side circuit board and the ground terminal provided on the plug side circuit board is electrically connected through the plug type and receptacle type connectors with the ground terminal provided on the receptacle side circuit board.
In such a plug type connector as described above, the conductive shell member has usually a pair of end portions in a direction along which the engaging projection formed on the insulating housing elongates (a direction along which the plug side signal contacts are arranged), each of which is electrically connected through a ground connecting portion thereof with the grounding portion of the plug side circuit board. With the end portions in the direction along which the engaging projection formed on the insulating housing elongates, each of which is connected through the ground connecting portion thereof with the grounding portion of the plug side circuit board, the conductive shell member is prevented from interfering with a condition wherein the plug side signal contacts arranged along the engaging projection formed on the insulating housing of the plug type connector are connected respectively with the signal terminals provided on the plug side circuit board.
In regard to the plug type connector thus provided with the conductive shell member having the end portions thereof in the direction along which the engaging projection formed on the insulating housing elongates, each of which is connected through the ground connecting portion thereof with the grounding portion of the plug side circuit board, it is feared that a middle portion of the conductive shell member located between the end portions of the conductive shell member in the direction along which the engaging projection formed on the insulating housing elongates is put at a position relatively distant from the grounding portion of the plug side circuit board and thereby a small potential difference arises between the middle portion of the conductive shell member and the grounding portion of the plug side circuit board when a high frequency signal transmitted through the plug side signal contact connected with the signal terminal provided on the plug side circuit board acts on the middle portion of the conductive shell member, so that a grounding characteristic of each of the plug side signal contacts corresponding to the middle portion of the conductive shell member is undesirably deteriorated. For dealing with such a problem, it is possible to provide an additional ground connecting portion on a portion other than the end portions of the conductive shell member. However, the ground connecting portions provided on the conductive shell member are severely restricted in their number and positions under a situation wherein the plug type connector is generally required to be miniaturized and therefore it is difficult to add the additional ground connecting portion to the conductive shell member having the end portions each including therein the ground connecting portion.
Under such a situation, there has been previously proposed an improved plug or receptacle type connector which is provided with a conductive shell member covering partially the outside of an insulating housing on which a plurality of plug or receptacle side signal contacts are arranged and in which not only a pair of end portions of the conductive shell member in a direction along which the plug or receptacle side contacts are arranged but also a plurality of portions located between the end portions of the conductive shell member are connected with a grounding portion of a circuit board to which the insulating housing is fixed, as disclosed in, for example, the Japanese patent application published before examination under publication number HEI 9-237656 (hereinafter, referred to as published prior art document JA).
In a plug type connector (1) disclosed in the published prior art document JA, a conductive shell member (shield (4)) is provided for covering partially the outside of an insulating housing (2) and some of a plurality of plug side signal contacts (terminals (3)) arranged on the insulating housing in a longitudinal direction of the same are operative to function as plug side ground contacts (ground terminals) connected with a grounding portion (a ground circuit) of a plug side circuit board (a printed circuit board).
A reed-like portion (9) is formed on each of portions of the conductive shell member corresponding respectively to the plug side ground contacts to be operative to come into press-contact with the plug side ground contact, so that the conductive shell member is electrically connected through the reed-like portions with the plug side ground contacts. As a result, the portions between a pair of the end portions of the conductive shell member in a direction along which the plug side signal contacts are arranged are connected through the plug side ground contacts with the grounding portion of the plug side circuit board.
Further, in a receptacle type connector (11) disclosed in the published prior art document JA, a conductive shell member (shield (14)) is provided for covering partially the outside of an insulating housing (12) and some of a plurality of receptacle side signal contacts (terminals (13)) arranged on the insulating housing in a longitudinal direction of the same are operative to function as receptacle side ground contacts (ground terminals) connected with a grounding portion (a ground circuit) of a receptacle side circuit board (a printed circuit board).
A reed-like portion (19) is formed on each of portions of the conductive shell member corresponding respectively to the receptacle side ground contacts to be operative to come into resilient press-contact with the plug side ground contact, so that the conductive shell member is electrically connected through the reed-like portions with the receptacle side ground contacts. As a result, the portions between a pair of the end portions of the conductive shell member in a direction along which the receptacle side signal contacts are arranged are connected through the receptacle side ground contacts with the grounding portion of the receptacle side circuit board.
In the previously proposed plug or receptacle type connector disclosed in the published prior art document JA wherein the portions between the end portions of the conductive shell member in the direction along which the plug or receptacle side signal contacts are arranged are connected with the grounding portion of the plug or receptacle side circuit board through the plug or receptacle side ground contacts with which the reed-like portions formed on the conductive shell member come into resilient press-contact respectively, since the electrical connection between the conductive shell member and the grounding portion of the plug or receptacle side circuit board is brought about with the reed-like portions formed on the conductive shell member put in resilient press-contact with the plug or receptacle side ground contacts, there is a disadvantage that reliability and stability in the electrical connection between the conductive shell member and the grounding portion of the plug or receptacle side circuit board are undesirably influenced by conditions of the resilient press-contact between each of the reed-like portions formed on the conductive shell member and the plug or receptacle side ground contact. For example, in the case where the reed-like portion formed on the conductive shell member is put in resilient press-contact with the plug or receptacle side ground contact without adequate pressure to the plug or receptacle side ground contact due to an improper mutual positional relationship between the reed-like portion and the plug or receptacle side ground contact or in the case wherein the reed-like portion formed on the conductive shell member is put in resilient press-contact with the plug or receptacle side ground contact with minute dust or dirt put between the reed-like portion and the plug or receptacle side ground contact, an electric resistance between the reed-like portion formed on the conductive shell member and the plug or receptacle side ground contact is increased so that a reliable and stable electrical connection between the conductive shell member and the grounding portion of the plug or receptacle side circuit board can not be obtained.
That is, with the previously proposed plug or receptacle type connector wherein the portions between the end portions of the conductive shell member in the direction along which the plug or receptacle side signal contacts are arranged are connected with the grounding portion of the plug or receptacle side circuit board through the plug or receptacle side ground contacts, it is feared that the electrical connection between the conductive shell member and the grounding portion of the plug or receptacle side circuit board is lacking in reliability and stability.